The invention relates to a small movable magnet type pump for use in pumping liquid such as water or kerosene.
A conventional small pump is an electromagnetic pump (a solenoid pump) that has an exciting coil for driving a magnetic piston in one direction and a return spring for returning the magnetic piston to the original position (For example, Japanese Patent Unexamined Publication (Kokai) Sho-55-142981).
The conventional electromagnetic pump combining the magnetic piston and the exciting coil must involve a mechanical return mechanism such as a spring, and this imposes the problem of not only complicating the mechanism but also making the structure large. In addition, to increase the operating force of the piston, the magnetic piston and the exciting coil must be large in structure. It is for this reason that small or very small pumps with sufficient liquid rasing power have been difficult to achieve in the conventional ordinary type electromagnetic pumps.